Why - only one caliper works

[Shugalou]

Thanks for the vid mr olds - funny enough I have already watched it (along with a bunch others)

Update:

I took a test light to the pin and sure as sh-t the light came on.

So looks like I need to re center it - these are the steps

Use a test light by attaching a clip to a positive contact on the vehicle and touch the point of the tester to the electrical connection of the combination valve. If the the light does not come on, the valve system is operating correctly and no further testing is required.

2.If the light does come on, this indicates that the pressure differential valve is stuck in the front or rear position.

3.Bleed the brake system to determine if the front or rear lines are blocked off. Set up one front wheel and one rear wheel for bleeding at the same time. Crack both bleeder screws and gently pump the pedal a few times.

4.The blocked side will trickle fluid out when the bleeder screw is cracked and the pedal pressed. An unblocked line will squirt fluid out the bleeder.

5.The lines that are clear must be left open and the blocked lines should have the bleeder screws tight to cause pressure to build up on that side. Be sure to use the standard bleeding procedures to prevent air from entering the system.

6.Slowly press the pedal with steady pressure a number of times until the light goes out; this will center the differential valve. You may also hear a pop come from the proportioning valve. This is the metering valve returning to its equalized position. When the light goes out, close the bleeder screw. (See fig. below)

A little pissed but I think I'm making progress...

Thanks for the help guys